Flexible printed circuit boards are of wide applications in various electronic devices, such as notebook computers, personal digital assistants, and mobile phones. A conventional flexible printed circuit board is composed of a plurality of conductors that are respectively covered by an insulation jacket and are arranged to juxtapose each other to form a flat structure. The flexible printed circuit board can be connected through electrical connectors or soldering for transmission of electronic signals.
Connecting electronic devices with a flexible printed circuit board is generally of no concern of waterproofing. However, waterproofing may become a problem especially for outdoor applications or for portable devices, such as mobile phones. Taking a mobile phone as an example, the mobile phone comprises a host device portion and a display screen portion that are connected to each other by a flexible printed circuit board that is attached to these portions through connectors or soldering. If waterproofing between the flexible printed circuit board and the host device portion or the display screen portion of the mobile phone is poor, then water may flow along the flexible printed circuit board into the host device portion and the display screen portion.
To effect waterproofing or resistance against humidity, conventionally, a rubber pad is provided as a waterproof or water-resistant member arranged between an enclosure of an electronic device and a flexible printed circuit board, whereby tight engagement is established between the flexible printed circuit board and the electronic device enclosure to achieve the desired effect of waterproofing or resistance against humidity.